1. Technical Field
The present invention generally relates to a film valve assembly and, more particularly, to a film valve assembly for a heating, ventilation and air conditioning system for a vehicle.
2. Decsription of the Prior Art
Conventional heating, ventilation and air conditioning (HVAC) systems for vehicles generally include a housing, an evaporator, a heater core having a housing, an evaporator assembly coupled to the housing, an evaporator, a heater core, an air inlet, a fan and various doors or mode valves for controlling the volume and direction of air flow and generating outlet air of a desired volume and temperature. Together these components receive, temper and direct the flow of forced air through several outlets or vents in the vehicle. The outlets through which the forced air ultimately exits are determined by the various doors which rotate or swing back and forth to open or close off openings and passages and cause air flow to be forced in one direction or another or a combination of both. Air may be directed to various areas of the car depending on the state of the mode valves. For example, air may be forced through outlets directed at the windshield in a defrost or defog mode, or through outlets directed at mid-height level in an air-conditioning mode, or to lower outlets directed to the floor in a heat mode, or various combinations thereof. Although, air of any temperature may be directed to and through any of them.
More recently, designs utilizing a flexible film valve rather than doors have been proposed for controlling volume and direction of air flow. Generally, the flexible film valve is disposed in a frame having rollers. The flexible film valve includes various apertures formed therein, is rolled back and forth over a first roller to cover or uncover various openings and may include an actuator for controlling the roller to wind and unwind the film valve.
Typical film valve designs are disclosed in U.S. Pat. No. 5,160,115 to Ito, et al. and U.S. Pat. No. 6,273,811 B1 to Pawlak, III. The '115 patent discloses an HVAC assembly including a film valve assembly having one roller with a biasing member and a motor. The '811 patent discloses an HVAC assembly including a film valve assembly having two rollers, each with a biasing member and a motor, and each operating a separate film valve. Such designs cause excessive wear on the film valve, the roller and the actuator, thereby increasing costs, and introduce noise in the system due to increased operational efforts required which may be displeasing to the driver of the vehicle.
In addition, the frame in which the film valve is situated typically comprises a static design specifically manufactured to be fitted onto an HVAC housing. Therefore, a frame must be designed and manufactured to meet each HVAC housing design, thereby increasing engineering and tooling cost.
FIG. 7 shows a portion 200 of a prior art ventilation system including a frame 202 defining a plurality of apertures 204, 206, 208, and 210. A fabric member or film valve 212 is wound and unwound relative to drive rollers 214, 216 interior of the frame 202. Idle rollers 218, 220, support the film valve 212 to seal the film valve 212 relative to the apertures 204, 206, 208, and 210. The film valve 212 seals with a flat surface 222 defined by the frame 202.
FIG. 10 shows a frame 202a of a prior art ventilation system defining surfaces 222a, 222b. A film valve (not shown) can slide across the surfaces 222a, 222b during movement relative to the frame 202a. During movement of the fabric member or film valve relative to the frame 202a, a noise is produced when debris becomes entrapped between the film valve 212 and surfaces 222a, 222b when the film valve slides across such surface.
The present invention is aimed at solving one or more of the problems described above.